A. de Oliveira Camargo, Flávio, Clesio Gianello, and Caio Vidor. 1997. “Time of Hydrolysis and Acid Concentration for Fractionation of Organic Nitrogen”. Pesquisa Agropecuaria Brasileira 32 (2):221-27. https://doi.org/10.1590/S1678-3921.pab1997.v32.4627.